This application claims priority from Korean Patent Application No. 10-2004-0064123, filed on Aug. 14, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
Apparatus and methods consistent with the present invention relate to probe-based data storage, and more particularly, to probe position error detection in a probe-based data storage system.
2. Description of the Related Art
A probe-based data storage device using a scanning probe microscopy (SPM) technology includes: a data storage medium; a probe, including a conductive tip for writing on or reading from the data storage medium and a cantilever in which the conductive tip is installed; an xy stage (scanner), carrying the data storage medium; a controller, controlling the probe and the xy stage; and a signal processor for the controller. In order to write and read data with high density and accuracy, a data tracking method having resolution greater than the size of unit data is required.
A conventional method of tracking a data position for writing or reading data in a probe-based high density data storage device using the SPM technology can be classified in the following three methods.
The first one is a method using mechanical or electrical signals from a data storage medium, which are distinguished from data to be written or read. This method is disclosed in U.S. Pat. Nos. 5,132,934, 5,396,483, 5,856,967, and 6,370,107, which teach forming of metal patterns or mechanical grooves on a data storage medium. However, it is difficult to precisely form the patterns or grooves on a data storage medium. Also, since mechanical grooves are used in a data read and write mechanism, a practical application range is narrow.
The second one is a method of displacing a center position of data recorded on a data storage medium by vibrating a probe or the data storage medium. This method, disclosed in U.S. Pat. No. 5,404,349, uses a modulation and demodulation scheme by vibrating a data storage medium with high frequency. However, it is difficult to vibrate a data storage medium with high frequency, and since the modulation and demodulation scheme is used, a detection circuit is complicated, and a detection time is delayed.
The third one is a method of using relative displacement between a center position of data recorded on a data storage medium and a probe writing or reading the data. This method, disclosed in U.S. Pat. Nos. 5,202,879 and 6,195,313, is disadvantageous in that data patterns must be very precisely recorded on a data storage medium. Particularly, since data cannot be continuously tracked according to U.S. Pat. No. 5,202,879, a data tracking speed is low. Accordingly, this method is very sensitive to external environments.